Over the past several months, Golf Digest has conducted extensive robotic testing on this year’s driver crop to determine how each brand performs against its predecessors and the current competition.
If there’s one common complaint readers have voiced, it’s that we usually run all of our testing at 95 mph, which is considered an average driver swing speed for a male amateur golfer.
Of course, there are plenty of golfers who swing it above and below this number, so we’ve expanded our testing this year to include a faster 105 mph swing speed. Adding even 10 mph can change the performance of a driver, so we’ve been comparing the two speeds (95 and 105 mph) to see how performance changes the faster you swing.
With Titleist releasing their GTS lineup later in the year, we figured it was worth going back and running the two-speed test again to see if GTS followed the same script or delivered a curveball.
Every build got faster and longer with the extra 10 mph. That part’s not surprising. What’s interesting is how even the carry gains are once you sort by loft.
The 8-degree tier picked up the most carry, on average, at 41.8 yards. The 9-degree tier added 39.3. The 10-degree tier, already the longest-carrying group at 95 mph, added the least at 33.4.
The higher-lofted builds were already closer to their trajectory ceiling at 95, so they had less room left to grow. Compared to other performance areas, carry distance was clean and easy to interpret.
The spin story is an interesting one, because it doesn’t move cleanly like the distance chart. For this test, we moved from a neutral angle of attack (AoA) at 95 mph to a slightly positive AoA (+1) at 105 mph to mimic what you’d likely see from a better player with more speed.
Going to a positive AoA will increase launch and decrease spin, in most cases, but we’re not seeing those things play out with GTS. In one instance (10-degree GTS4), spin dropped more than 200 rpms, but the rest of the lofts and models either saw spin stay flat or slightly increase.
What this means, especially for those with a neutral or slightly positive AoA, is that you can swing harder and not see a large spin delta. Remember, the spin numbers you’re looking at are an average of nine impact locations on the face.
The SDEI (Spin Degradation Index) is our shorthand for how consistently a driver delivers spin across the face, comparing each off-center zone back to the middle-center strike. Lower is better. Seven of the nine GTS builds got worse at 105 mph, by an average of 13 rpm. Two improved, both at 8 degrees.
The real-world translation: A build that felt steady on mishits at 95 mph won’t necessarily feel that way once the speed climbs. Off-center contact costs more at higher speed than the on-paper forgiveness numbers would suggest.
All of this is what you’d expect from a driver at faster speeds. That being said, the spin deltas we saw on the robot were minimal, meaning you don’t have to sweat big jumps in spin from one mis-hit zone to the next.
Titleist has been working on tuning spin, and this confirms what they are doing is working.
Eight of the nine builds saw dispersion expand at 105 mph, and the 8-degree tier spread out the most by a wide margin. The GTS 4’s 8-degree build nearly doubled its dispersion area, from 704 to 1,377 square feet, the widest swing in either direction anywhere in the test.
Interestingly enough, only one build tightened: GTS 4 at 10 degrees, which actually got more consistent at the higher speed. As we saw with spin, there’s no clean loft-based rule here either.
Outside of the 8-degree GTS4 at 105 mph, most of the drivers saw minimal gains in the dispersion department, even when speed increased.
One pattern from this test is cleaner than the rest. Descent angle functions as a floor, roughly 30 degrees, below which drivers tend to give up carry relative to their ball speed.
At 95 mph, only the 10-degree builds cleared the threshold. At 105, the 9-degree tier catches up too, averaging 30.3 degrees. The 8-degree tier never gets there, averaging just 26.4 degrees even with the extra speed.
The takeaway from this test is that spin, dispersion and face stability all behave differently depending on which specific loft and model combination you’re looking at, not on some clean rule that applies across the board.
The one thing that does hold steady is loft’s relationship to trajectory: a 105-mph golfer in an 8-degree head is chasing the same descent-angle shortfall as a 95-mph swinger who’s under-lofted.
It further confirms that, at the end of the day, you need a strong fitter in your corner to find the best model and loft combination for your game, especially if you’re chasing more speed.